Most psychology research that deal with gay
men dichotomize the sex roles as Top and Bottom (if they differentiate
among gay men at all) - preference for insertive anal intercourse and
preference for receptive anal intercourse respectively. This paper summarizes
a study that tested a more elaborate categorization, and finds that
sex role preference is correlated with differences in physical preferences
for a sexual partner among gay men, suggesting that the hypothesized
categorization is meaningful. The data suggests that sex roles should
be thought of as a continuous spectrum that map onto a continuous spectrum
of physical preferences.

The new categorization tested includes 6
categories:
1) Only Bottom
2) Versatile, but prefer Bottom
3) Versatile, equal
4) Versatile, but prefer Top
5) Only Top
6) Never had anal sex / Don't Know

All respondents were volunteers recruited
from www.gay.com chat rooms over the period of 1/25/02 to 1/27/02. They
were asked to participate in an online questionnaire. A total of 396
respondents completed the survey. The average age of respondents was
around 33:

The average self-reported height of respondents
was 5'10, and the average weight was 180 lbs. Both these statistics
closely match national averages for men above the age of 20 - 5'9 and
180 lbs respectively.

Here is the distribution of how respondents
categorized themselves into the more elaborate sex role categories:

Many gay men feel that there are more Bottoms
than Tops, and the point of the study wasn't to prove this one way or
another. The milieu of gay.com may have skewed the proportions. But
the point of the study was to see whether preference for certain physical
traits were different among individuals among the different categories
rather than finding out the actual distribution (which is a much tougher
question because it's hard to remove the bias of where you solicit your
respondents).

The data showed that while most gay
men preferred men who were around their age, gay men who identified
as Only Bottoms prefer significantly older men than Only Tops. Notice
that the distribution is negatively skewed for Only Tops and is positively
skewed for Only Bottoms. The 3 Versatiles have a normal distribution
centered on "Around my Age", and were not significantly different
from each other.

We see the same trend in height preference.
Only Tops prefer significantly shorter men than Only Bottoms who in turn
tend to prefer significantly taller men.

When asked to indicate the desired weight for
a male who is 5'11, Only Tops preferred significantly lighter men than
Only Bottoms who preferred significantly heavier men.

And finally, we see the same trend for preference
for hairiness. Only Tops are significantly more likely to prefer smooth
men than Only Bottoms who tend to prefer very hairy men.

In a pilot study with only 20 subjects and
a dichotomized sex role preference, Damon (2000) found trends that power
motivations correlated with sex role preference. In particular, he suggested
that men who prefer insertive anal intercourse like to exert power over
their sexual partners during sexual intercourse, while men who prefer
receptive anal intercourse like to be overpowered.

Data from the current study supports this theory. Age, height,
weight and hairiness are indicators of masculinity. Older, hairier, taller
and more solid men are considered to be more masculine than younger, smoother,
shorter and lighter men. Data from the current study suggests that Only
Tops seek out sexual partners with less masculine features, while Only
Bottoms seek out sexual partners with more masculine features. One might
suggest that Only Tops seek out sexual partners with feminine qualities
while Only Bottoms seek out sexual partners with masculine qualities.

Respondents were also asked whether they preferred
their sexual activities to be gentle, rough or in-between. It was found
that Only Bottoms and Versatiles (prefer Bottom) were more likely to prefer
rough sex than the other 3 categories, again suggesting that receptive
anal intercourse is linked with a desire to be overpowered.

Not only does the data show significant differences
in physical preferences between Only Tops and Only Bottoms, but the data
also shows that the 3 Versatiles, for the most part, modulate between
these two extremes in a fairly linear manner. For example, consider this
excerpted height preference table:

So if we think of Only Tops as preferring feminine
traits and Only Bottoms as preferring masculine traits, then we have evidence
that the more a gay man prefers the Bottom role, the more he prefers masculine
attributes (older, taller, heavier, hairier) in a partner, and the more
he prefers the Top role, the more he prefers feminine attributes (younger,
shorter, lighter, smoother) in a partner.

Critics may point out that maybe Bottoms who prefer older
partners become Tops who prefer younger partners as they get older, or
that Tops in general are older than Bottoms. An ANOVA using sex role preference
as the grouping variable and age as the dependent variable found no significant
age difference between the 5 sex role groups (F[5,388]=1.60, p=.16). Also,
Weinrich (1992) showed that early childhood play preferences were good
indicators of sex role preference in adult gay men. These two sets of
data together imply that sex role preferences among gay men are determined
early in life and do not change.

In conclusion, instead of the Top and Bottom dichotomy,
the data shows that there seems to be a fairly continuous spectrum of
sex role preferences among gay men that map fairly consistently onto a
continuous spectrum of physical preferences. Of course, the bigger question
now is what biological or developmental differences map onto sex role
preference, and what leads some gay men to prefer insertive anal intercourse
rather than receptive anal intercourse.

Note (added June 2007): Looking back,
this was such an interesting data set. My perspective of sexuality has
changed a great deal since 2002 however. I am much more of a social constructivist
than a biological determinist. If you found this article interesting,
I would recommend a more
recent article I wrote where I explore the social
nature of sexuality.

References:

Damon, Will (2001). The relations of power and intimacy
motives to genitoerotic role preferences in gay men: A pilot study. Canadian
Journal of Human Sexuality. 2000 Vol 9(1) 15-30.